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cleaning cycle, reducing operating costs, making sure that chemical and biological processes and membrane
processes achieve the best effects.
2.Introduction of the project
2.1 Design ideas of the brewery wastewater treatment plant
The process of wastewater treatment was according to the characteristics of wastewater and the effluent
requirements. The brewery used UASB process as pretreatment, and CODCr reducedfrom 2000~2500mg/L to500~1000mg/L, then the UASB effluent entered the MBR system for deep treatment, the water quality of
effluent standards for the landscape and recreation area.
2.2 Treatment scale:4,000t per day, outflow rate: 208m3/h.
2.3 Treatment process of MBR
2.3.1 The process was reliable, simple operation, stable effluent quality, low operation cost, highly degree of
automation. According to the characteristics of influent quality and effluent quality requirements, we used the
process flow shown in Fig1.
2.3.2 Description of the process
(1) Process feature
Multi-segment AO+MBR process was used. The process could effectively degrade Ammonia-N and organicmatter in beer wastewater, anoxic segment and return activated sludge system could enhance the effects of
nitrification. This system could achieve nitrogen removal functions under nitrification and denitrification.
Biological phosphorus removal process includes aerobic pool and anaerobic pool. In the anaerobic pool, storing
phosphorus germ transformed biodegradable micro-organisms into the body of the carbon source, and consume
intracellular storage of poly-phosphate, at the same time release of orthophosphate to the water body. In the
aerobic pool, storing phosphorus germ consumed carbon stored in cell, and transformed solubility of inorganic
phosphorus into the intracellular storage of poly-phosphate, so as to achieve phosphorus removal function(Zeng,
Yiming, 2007). The high interceptor capability of membrane made sludge concentration achieving higher levels
in MBR, increasing the effect of removal of ammonia-N and organic matter and improve effluent quality.
(2) System structure
The system included biochemical system, membrane filtration system, membrane cleaning system, control
system, electrical and mechanical systems. Biochemical systems included anoxic stage and aerobic stage, thereturned sludge and mud discharging systems, water quality parameter testing systems etc. Adjusting the aeration
volume and drug flow rate of pre-process by on-line detection of dissolved oxygen, pH and other parameters.
(3) Membrane module
Membrane modules were external pressure submerged hollow fiber membrane made by Tianjin MOTIMO
Membrane Technology Co.,Ltd. Hollow fiber membrane was made of polyvinylidene fluoride (PVDF), and it
was resistant to sodium hypochlorite, chlorine dioxide and other oxidants, at the same time it had long life
performance. We can use common fungicides, such as NaClO and hydrochloric acid, as a bactericidal and
membrane cleaning agent. Membrane working pressure was low, and at ranging of 10 ~ 50kPa, so its energy
consumption was lower than other technologies. The whole system of water production adopted automatic
control, 8min run and 2min stop.
2.3.3 Raw water quality(1) MBR influent water source: UASB system effluent.
(2) After pre-treatment of UASB process, quality of wastewater include CODCrconcentration of 500 ~ 1000 mg /
L, Ammonia-N concentration of 20 ~ 30mg / L, et al.
2.3.4 Outflow quality requirements
The outflow quality meet the standard of landscaping water reuse, Main water indicators: CODCr40 mg / L,
BOD510 mg / L, SS 10 mg / L, NH4-N 5 mg / L, TP0.5 mg / L, TKN 10mg / L.
3. Effect of the operation
3.1 Analysis of influent and effluent quality
3.1.1 Effect of the CODCrremoval by MBR
As shown in figure 2, the CODCrof feed water at the maximum value of 1626mg/L and the minimum value of
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641.9mg/L, while it is at mean value of 1018.95mg/L; the CODCr of permeate water an average value of
40.20mg/L, its minimum value reach to 4mg/L, and the average removal rate is up to 96.05%. COD Crof the test
water production is higher than 50mg/L during the 13 ~ 17 times because of beer production equipment
maintenance, no waste water and MBR system stopped running for a week. At the start-up phase, the sludge
concentration is low and microbial performance unadapted to wastewater quality, so treatment efficiency
declined. Running through a week to restore, in the case of fluctuations in feed water quality, permeate water
quality is stable and MBR shows a stronger tolerance to fluctuation loading.
3.1.2 Effect of Ammonia-N removal
As shown in figure 3, the Ammonia-N concentration of feed water was averaged 23.69mg/L, and the
Ammonia-N concentration of permeate water was averaged 1.903mg/L, removal efficiency reach to 91.97%. In
the two-month monitoring period, permeate water was tested 25 times, and the ammonia-N concentration
exceeded 5mg/L for only two times. The analysis concluded that Ammonia-N concentration high of initial
testing was due to instability of the feed water, and resulted in large fluctuations of dissolved oxygen
concentration in aerobic pool, affecting the nitration reaction, thus leading to instability in the value of the
Ammonia-N of permeate water. When the feed water was continuous and stable, aerobic pool dissolved oxygen
concentration was controlled at the range of 2~4mg/L by adjusting the air volume. After half month running the
Ammonia-N concentration reduced to 1mg/L and remained stable.
3.1.3 pHThe pH value of feed water was stable, with an average 7.69, which was suitable for microbial growth. The pH
of the permeate water was averaged 8.35, somewhat higher than the feed water, which is due to micro-organisms
consuming of organic acids in the process of decomposition of organic matter.
3.1.4 Effect of Nitrogen and Phosphorus Removal
The mechanism of T-P removal: The T-P concentration was tested five times, and the T-P concentration of feed
water was changed from 0.63mg/L to 14.76mg/L, but the T-P concentration of permeate water was below
0.3mg/L stably. The T-N concentration of feed water was at the range of 19.5~41.1mg/L, the permeate water T-N
was at the range of 0.6~ 2.3mg/L.The test result indicated that it was ideal effect of nitrogen and phosphorus
removal, and this craft was reasonable.
3.1.5 Turbidity removal
Turbidity was an very important indicator of the senses in wastewater reuse. After two months testing, theturbidity of permeate water was 0.24~0.52NTU, the permeate water was clear and could meet the requirements
of discharge standard.
3.2 sludge loading of biochemical pool
Sludge concentration of the system was 6000~10000mg/L. Sludge loading as an important biochemical
parameters of the system, which could be used to estimate the biochemical process operating conditions of the
MBR and be adjusted operating parameters, by calculating the sludge loading.
As shown in table 1, it showed that the sludge CODCr loading averaged 0.286KgCOD/KgMLSS d, sludge load
fluctuated from 0.177 to 0.429. Owing to the fluctuation of feed water quality, the impact load on the sludge was
large, which led to bad settleability of activated sludge.
3.3 The regulation of operating parameters and control of membrane fouling
3.3.1 Dissolved oxygen in aerobic pool
At the initial operation of the project, dissolved oxygen concentration fluctuated at the range of 0.02~6mg/L, and
it was very unstable and presented parabolic-type cycle trend. This fluctuation was caused by the unbalanced
quantity between feed water and permeate water: when producing water, the biochemical pool was at a low level
in a very short time, and then stopped producing water, in this situation a continuous influent caused dissolved
oxygen concentration of aerobic pool decline to 0.5mg/L below sharply; when the biochemical pool at a high
water level, the wastewater of system stopped flowing into MBR. Due to excessive aeration, dissolved oxygen
rose to more than 5mg/L sharply, which affected not only the normal microbial decomposition of organic
material but also wasting of electrical energy.
There were literatures indicating that: (1) when the dissolved oxygen concentration was higher than 4mg/L,
microbial decomposition of carbohydrates increased, these hydrophobic substances would be adsorbed on the
wall of the membrane pore, and this covering layer on membrane surface was difficult to wipe off by shearing
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force. In addition, the adsorption increased membrane fouling and made cake layer thicker, therefore the
frequency of membrane cleaning increased (Zeng, 2007); (2) when dissolved oxygen concentration was lower
than 0.5mg/L, the aerobic bacteria was on anaerobic condition in aerobic pool, and this anaerobic condition
would facilitate the growth of filamentous bacteria and cause sludge bulking, which also aggravated membrane
fouling (Gao, 2001, P12~15). By means of summarizing the operational experience, adjusting the height of
liquid indicator, frequently short-term inflow, reducing the fluctuations of dissolved oxygen concentration, the
dissolved oxygen concentration could be kept on the rang of 2~3mg/L. In this condition, micro-organisms couldkeep the biochemical effects and sludge properties ideal.
3.3.2 Aeration intensity of the membrane tank
Adopting the hole with coarse aeration tube at the bottom of membrane modules could maintain membrane fiber
in mixture turbulent fluctuation in wastewater, slow down the sludge deposited on the membrane surface,
controll membrane fouling and prolong membrane useful time (Zhang, 2004, P11~15). Large aeration increased
energy consumption, though small aeration increased membrane fouling. According to experiments with
membrane filtration resistance and analysis of sludge characteristics, we concluded that the best ratio of
membrane aeration volume and permeate water volume was 12:1 ~ 15:1.
3.3.3 Sludge concentration of aerobic tank and membrane tank
As shown in figure 4, the MLSS variation tendency of membrane tank and anoxic tank MLSS was shown in
Figure 4. At the beginning the sludge concentration of membrane tank was 11690mg/L and the anoxic tank was9660mg/L. It indicated that sludge concentration was higher, sludge settling was not well, and also the floc size
was very small, so it accelerated membrane fouling, increased membrane filtration pressure and flux reduce. A
certain increase of sludge concentration could improve the efficiency of the reactor, but with the increase of
sludge concentration, leading to the mixture viscosity became greater and membrane filtration resistance
increased, and the membrane flux was affected (Liu, 2001, P20~24). The sludge concentration of 6~8g/L was
better.
3.3.4 Settling Velocity SV30
During the experiment, SV30 was tested once everyday, and the SV30 of membrane tank was at the range of
93%~98%, SVI at 100~160ml/g. As the sludge concentration of biochemical tank was high and settling was very
different from the conventional activated sludge process, the sludge settling characteristics have relationship on
the extent of membrane fouling. Sludge was divided into granular sludge and floc sludge by aggregation
morphology, and the settling performance of granular sludge was better than floc sludge, because it was easier to
reverse back into the mixture from membrane surface, and it was difficult to form a cake layer. The specific
surface of floc sludge was larger than the granular sludge, which meant that it was more likely to extracellular
polymeric substances adsorbed on the membrane surface, comparing to granular sludge more difficult to lead to
fouling of adsorption (Zheng, 2001, P41~44). Improving the sludge settling was also a way to reduce the
membrane fouling. Experiment showed that the sludge concentration was controlled at the range of 6~8g/L,
sludge SV30 below 80%, which may slow down the speed of membrane fouling.
4. Conclusion
1) Using MBR method treating brewery wastewater achieved good effect of CODCr removal, NH4-N removal
and T-P removal, and the index of permeate water were: CODCr
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Treatment[J].China water & wastewater, 22(16): 62~66.
Liu rui, Huang xia, et al. (2001). A Comparison between a Submerged Membrane Bioreactor and a Conventional
Activated Sludge Process[J].Chinese Journal of Environmental Science, 22(3):20~24.
Zeng yi-ming. (2007).Membrane bio-reactor technology. Bei jing: National Defence Industry Press (chapter 4).
Zhang chuan-yi, Wang yong, et al. (2004). Experimental study on economical aeration intensity in a submerged
membrane bioreactor[J].Membrane science and technology. 24(5): 11~15.
Zheng xiang, Fan yao-bo. (2001). Optimization of the Operation Parameters on MBR and Membrane Fouling
Control[J]. Water & Wastewater engineering, 27(4): 41~44.
Table 1. Sludge concentration and Sludge loading
1 2 3 4 5 6 7 8 9
MLSS(mg/L)9660 6120 6922 6262 7800 6726 8016 7802 7774
Sludge loading
(Kg COD/Kg
MLSSd)
0.225
0.302 0.363 0.224 0.354 0.217 0.429 0.283 0.177
Returned sludge
Surplus sludge
`
Figure 1. Schematic diagram of the project
Anaerobic
pool
Pretreatme
nt pool
Sump
well
Adjustin
g pool
UASB Anoxic
pool 1
Sludge
dewatering
Membrane
pool l
Aerobic
pool 2
Aerobic
pool 1
Anoxic
pool 2
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Figure 2. Effect of the CODCrremoval by MBR
Figure 3. Ammonia-N of MBR system influent and effluent
0
300
600
900
1200
1500
1800
1 5 9 13 17 21 25
Test frequency
COD(mg/l)
Feed water
Permeate water
0
5
10
15
20
25
30
35
1 5 9 13 17 21 25
Test frequency
Ammonia-N(mg/l)
Feed water
Permeate water
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Figure 4. The sludge concentration in Anoxic tank and Membrane tank
2000
4000
6000
8000
10000
12000
14000
1 5 9 13 17 21 25Test frequency
Sludgeconcentration
(mg/l) Anoxic tank
Membrane tank
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